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Published on: August 24, 2013
RAD50 missense variants differentially affect the DNA damage response and mitotic progression
Hanna Redeker1, Swantje Kebel1, Lea Völkening1
1Gynaecology Research Unit, Hannover Medical School, Germany.
Abstract:
RAD50 is the central protein of the MRN complex and crucial in DNA double-strand break repair. RAD50 deficiency causes a genomic instability disorder characterized by microcephaly and stunted growth. Using lentiviral constructs, we investigated whether cancer-related RAD50 missense variants can complement the delayed damage response after exposure to the chemotherapeutic agent epirubicin and/or mitotic progression in RAD50-deficient fibroblasts. Eight missense variants, all capable of forming an MRN complex, supported the DNA damage response and mitotic features to different extents, indicating these functions are separable. Three variants showed both an impaired epirubicin response and slowed cell division in the likely pathogenic range. Assessing RAD50 missense variants with distinct functional readouts may help to further elucidate their differential roles in immunodeficiency and cancer and could improve therapeutic strategies. Impact statement RAD50 has a strong impact on DNA repair and cancer therapy. Here, we analyse RAD50 missense variants at four functional levels. Some variants showed an impaired epirubicin response and mitotic progression in the pathological range, while for others these endpoints were separable. Functional heterogeneity of RAD50 variants could contribute to clinical variability.
Insights
RAD50 protein variants impact DNA repair and cell division differently. Some RAD50 variants impair responses to chemotherapy and cell cycle progression, suggesting distinct roles in genomic instability and cancer.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- RAD50 is essential for DNA double-strand break repair via the MRN complex.
- RAD50 deficiency leads to genomic instability, microcephaly, and stunted growth.
Purpose of the Study:
- To investigate if cancer-related RAD50 missense variants can restore DNA damage response and mitotic progression in RAD50-deficient cells.
- To analyze the functional impact of RAD50 variants on epirubicin treatment response and cell division.
Main Methods:
- Utilized lentiviral constructs to introduce RAD50 missense variants into RAD50-deficient fibroblasts.
- Assessed complementation of DNA damage response after epirubicin exposure.
- Evaluated mitotic progression in cells expressing RAD50 variants.
Main Results:
- Eight RAD50 missense variants, capable of forming the MRN complex, partially restored DNA damage response and mitotic features.
- Three variants demonstrated impaired epirubicin response and slowed cell division, falling within the likely pathogenic range.
- Functional analysis revealed separable roles for RAD50 in DNA repair and cell cycle progression.
Conclusions:
- Functional heterogeneity exists among RAD50 missense variants, impacting DNA repair and cell division distinctly.
- Assessing RAD50 variants at multiple functional levels can clarify their roles in diseases like immunodeficiency and cancer.
- Understanding variant-specific functions may inform improved therapeutic strategies for cancer and related disorders.
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